A car bomb exploded Thursday across from Hezbollah’s main political office in southern Beirut, killing at least five people and wounding dozens.

Lebanese army officials said the estimated 45-pound bomb exploded in a Jeep Cherokee shortly after 4 p.m. and that the vehicle “contained body parts,” which led authorities to speculate that the explosion was the work of a suicide bomber.

Political violence tied to the civil war in Syria has essentially shattered a nation already divided on sectarian lines, with many Sunni Muslims supporting the rebellion against Syrian President Bashar Assad while the Shiite Muslim community, dominated by Hezbollah, has cast its lot with Assad. Both sides have seen communities targeted by bombs and rocket fire, and last week a prominent Sunni politician, former Finance Minister Mohammed Chatah, was killed in a car bombing in downtown Beirut.

The scene of Thursday’s blast exemplified the complexity of Lebanon’s politics, with army units and government rescue crews _ symbols of the Lebanese state _ mixing with dozens of armed and unarmed security personnel deployed to the area by Hezbollah, which operates as a better-organized state within a state. As is common in south Beirut, which Hezbollah controls, the soldiers deferred to the Shiite militants on matters of security.

The bomb ripped the facade off an apartment building and burned several cars a few yards from the offices of Hezbollah’s politburo, which represents the group’s political interests. The group said that none of its personnel had been injured, although Hezbollah commonly obscures its casualties for security reasons.

Bilal Farhat, a member of Parliament from Hezbollah’s political bloc, said the group would be patient in responding to the blast – despite an increasingly angry Shiite community that’s been hit by three such bombs in the past few months – because “despite the wounds . . . Lebanon won’t benefit from any bloodshed.”

The bomb came a day after Lebanese authorities confirmed the arrest of a Saudi militant in connection with November’s double suicide bombing of the Iranian Embassy in Beirut _ which killed 23 people, including an Iranian diplomat _ just a mile or so from Thursday’s bombing.

Majid al Majid, allegedly the head of the Abdullah Azzam Brigades, a group that describes itself as al Qaida’s representative in Lebanon, was arrested sometime in early December; authorities have refused to say when or where.

“We believe that this prisoner is” Majid, said a Lebanese security official, who added that the government hadn’t intended to make the announcement for another week, while the suspect was questioned, in order not to alert members of his group. Because of the news blackout, the official spoke only on the condition of anonymity.

Majid was named on a 2009 list of Saudi Arabia’s 85 most wanted militants with al Qaida links, and he’d been long rumored to be living in Lebanon’s largest Palestinian refugee camp, Ain el Hilweh, in the southern city of Sidon.

American intelligence officials told the Reuters news service that the news of the arrest was thought to be credible and that Lebanese law enforcement was interrogating Majid.

The Abdullah Azzam Brigades, which announced its first operations in 2005, was the result of a decision by the then head of al Qaida in Iraq, Abu Musab al Zarqawi, to send several Lebanese and Saudi militants to Ain el Hilweh to form a new militant organization. The group had taken credit for a number of small-scale attacks in Lebanon, Oman, Jordan and Egypt before the bombing of the Iranian Embassy on Nov. 19.

At the time, the group put out a statement demanding that Iran and its Lebanese ally Hezbollah immediately halt their overt military support for Assad.

The Iranian Parliament released a statement Wednesday thanking Lebanon for the arrest, while Saudi Arabia expressed hope that Majid, if identified, would be quickly extradited to his homeland to face terrorism charges, a notion that some Hezbollah supporters in Lebanon found unsettling.

“A country that respects its sovereignty and its laws does not give them up to respond to another nation’s request, especially if the detainee is a dangerous person that looked for inciting strife,” Slieman Franjieh, a member of Parliament allied with Hezbollah, said in a statement.

One Lebanese news account said Majid had left the relative safety of Ain el Hilweh – by tradition, the Lebanese military cannot enter the camp – about a month ago and traveled to Syria to meet with Abu Mohammed al Jolani, the head of the Nusra Front, an al Qaida-affiliated Syrian rebel group. The report said Majid was arrested as he returned from Syria, but it didn’t say when. The account couldn’t be independently confirmed.

Another local news report said a series of attacks on Lebanese army positions in Sidon more than two weeks ago was retaliation for the arrest and that a suicide bombing that killed a Lebanese soldier was part of an attempt to free Majid from the custody of military intelligence at its headquarters in Sidon.